Mast Cell-Derived Histamine Regulates Liver Ketogenesis via Oleoylethanolamide Signaling

？ Fasting stimulates extra-hepatic mast cells to release histamine ？ Histamine travels through the hepatic portal system and activates liver H 1 receptors ？ H 1-receptor activation triggers OEA biosynthesis in liver ？ Histamine-dependent OEA signaling enhances fasting-induced ketogenesi